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William Heberden (1710--1801), in 1768, described angina pectoris, the classic symptom of ischemic heart disease, 150 years after the discovery of the coronary circulation by William Harvey (1578-1657). Another 110 years had elapsed before the first antemortem diagnosis (confirmed at autopsy) of coronary thrombosis was reported by Adam Hammer in 1878. The patient was a 34 year old man who died some 19 hours after a sudden collapse. Although the patient's clinical features were atypical (such as the absence of angina and the presence of complete heart block) and the autopsy showed vegetative aortic endocarditis that appeared to be causally related to the thrombotic coronary occlusion, Hammer's astute and carefully reasoned bedside diagnosis was history-making and deserves to be so recognized.
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PMID:Centenary of the first correct antemortem diagnosis of coronary thrombosis by Adam Hammer (1818--1878): English translation of the original report. 36 Aug 11

Although both sudden death and acute myocardial infarction are almost always associated with long-standing obstructive coronary artery disease, both may originate in the myocardium. Spasm has been suggested as a factor contributing to sudden death. Not all persons dying of acute myocardial infarction have narrowed coronary arteries, nor do all persons with obstructed arteries die of heart disease. The first phase of acute myocardial infarction may well involve myocardial necrosis, followed by stasis and collapse of collateral circulation and occasionally by coronary occlusion.
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PMID:Sudden death and acute myocardial infarction: clues to differences in pathophysiology. 70 7

Compton backscatter imaging (CBI) is a technique that uses x-rays scattered from the closed-chest surface of the heart to obtain high frequency (5 msec) and high precision (+/- 0.1 mm SD) measurements of regional surface displacements and velocities. These measurements are acquired in a three-dimensional format that allows the reconstruction of the epicardial surface and the creation of color coded displacement and velocity maps at many time points during the cardiac cycle. Applications of the technique are shown to characterize detailed regional normal wall displacement and velocity patterns, and the significant alteration of those patterns after coronary embolization. The technique is also applied to the characterization of early diastolic wall dynamics. CBI measurements show that a brief and somewhat paradoxical inward displacement of the anterior ventricular wall occurs during early diastole in normal canines. The wall dynamics associated with this inward displacement suggest a brief collapse of the ventricle subsequent to aortic valve closure. Diastolic collapse velocities and displacements are significantly altered subsequent to coronary occlusion with mean and maximum collapse velocities decreasing by 50% and concomitant inward displacements decreasing by 40%. Data acquisition with CBI is non-invasive, does not require contrast agents or radioisotopes, and uses low irradiation levels (125 kVp, 3-5 ma). The average radiation dose to the heart for a typical study is 250 mrem, significantly lower than that of other radiation based imaging techniques.
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PMID:High precision Compton backscatter maps of myocardial wall dynamics. Theory and applications. 280 18

Because the left ventricular "area at risk" is the most important determinant of ultimate infarct size, it would be useful to know the size of the area at risk during acute myocardial infarction to make therapeutic decisions. We therefore performed a series of experiments in four groups of dogs. In group I dogs (n = 15) we attempted to determine whether current methods of assessing left ventricular function during acute myocardial infarction reflect the true size of the area at risk. At each of two to five sequential stages, a more proximal coronary occlusion was performed to produce a larger area at risk until cardiovascular collapse occurred. At each stage, the area at risk (measured by myocardial contrast echocardiography), hemodynamic variables, and left ventricular ejection fraction (LVEF) were measured. Hemodynamic variables became abnormal when the area at risk was large (25% to 40% of the left ventricle), whereas LVEF became abnormal when the area at risk was of moderate size (18%). When cardiac output and LVEF were normalized to baseline values, a close inverse relationship was noted between these variables and area at risk. In contrast, there was a poor relationship between normalized mean arterial pressure and area at risk (r = .42). In group II dogs (n = 9) the area at risk was measured serially over 6 hr after coronary occlusion. The size of the area at risk remained unchanged regardless of the transmural extent of the ultimate infarct. The circumferential endocardial extent of the area at risk closely predicted the circumferential endocardial extent of the infarct at 6 hr in eight of nine dogs that developed an infarct. Group III dogs (n = 7) underwent the same protocol as group II dogs, but the duration of occlusion was 3 hr. The circumferential endocardial extent of the area at risk closely predicted the circumferential endocardial extent of the infarct. Group IV dogs (n = 5) underwent subtotal coronary occlusion. Although regional wall motion abnormalities were noted in this group, no area at risk could be defined. We conclude that although a close inverse relationship is noted between normalized cardiac output and area at risk, the absolute values for cardiac output and other hemodynamic variables become abnormal only when the area at risk is large (25% to 40%); measurement of LVEF may provide a better assessment of the size of the area at risk than hemodynamic variables.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The importance of defining left ventricular area at risk in vivo during acute myocardial infarction: an experimental evaluation with myocardial contrast two-dimensional echocardiography. 303 76

Acute coronary obstruction occurred in two patients during coronary angiography. In one case the obstruction was in the left main coronary artery; in the other it was close to the origin of the left anterior descending artery. In both cases acute cardiac ischaemia ensued, with electromechanical dissociation and collapse, which was not reversible by resuscitation. Rapid disobliteration of the occluded coronary artery was done with a guide-wire pushed through the obstruction via the coronary catheter. The recanalisation was completed by an intracoronary perfusion of streptokinase in one case. In both cases recovery was rapid and spectacular. The occurrence of acute ischaemia during coronary angiography should suggest accidental coronary occlusion. If a thromboembolic origin is suspected, transluminal disobliteration should be attempted. It is simple and can reverse a dangerous condition.
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PMID:Acute coronary occlusion during coronary angiography in two cases. Treatment by transluminal disobliteration. 646 May 14

Mechanical support for acute regional ischemia without hemodynamic collapse may be achieved percutaneously with an intraaortic balloon pump (IABP) or with transseptal left ventricular assist (TLVA) while awaiting revascularization. The relative benefits of these two percutaneous transfemoral techniques for the treatment of ischemia were compared in a representative animal model. During 90 minutes of regional coronary occlusion, four groups of 8 pigs were treated with either no support (control), IABP, TLVA, or both IABP and TLVA. Cardioplegic arrest for 30 minutes to simulate coronary grafting was followed by 180 minutes of global reperfusion on bypass. In all groups regional wall motion and interstitial pH in the area at risk were significantly depressed with ischemia, but wall motion fully recovered after reperfusion. However, histochemical staining of the area of necrosis/area at risk was significantly reduced with IABP versus control (20.2% versus 34.1%; p < 0.05) and further significantly reduced with TLVA and IABP + TLVA (10.7% and 6.7% versus IABP alone; p < 0.05). We conclude that in supporting even a modest-sized myocardial region at risk (12% of the left ventricle) the area that went on to infarction was significantly reduced with the use of TLVA over IABP. Regional wall motion and myocardial pH measurements did not reflect this difference in the early reperfusion period. The benefit of TLVA over IABP during more extensive or prolonged ischemia may have real clinical significance.
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PMID:Enhanced preservation of acutely ischemic myocardium with transseptal left ventricular assist. 814 23

A neonate who presented with circulatory collapse was found to have myocardial infarction caused by thrombotic occlusion of the left main coronary artery. At autopsy, a thrombus was found in the ductus venosus making paradoxical embolism through the foramen ovale the most likely mechanism of coronary occlusion.
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PMID:Paradoxical embolism causing fatal myocardial infarction in a newborn infant. 1151 10

Transcatheter aortic valve implantation (TAVI) is a highly effective procedure for selected patients who are at high risk for aortic valve replacement; however, the incidence of severe complications is still relevant. Coronary occlusion during TAVI is a life-threatening complication that requires immediate diagnosis and treatment. We report the case of an 87-years-old woman affected by severe aortic stenosis, symptomatic for refractory heart failure, who underwent urgent balloon aortic valvuloplasty and subsequent elective transapical aortic valve implantation. Valve deployment was complicated by cardiac arrest and hemodynamic collapse, and left main coronary artery occlusion was recognized and successfully recovered by balloon angioplasty and stent implantation. Patient is alive and well 6 months after procedure.
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PMID:Trans-apical aortic valve implantation complicated by left main occlusion. 2195 60

Transcatheter aortic valve replacement (TAVR) is performed with increasing frequency in the United States since Food and Drug Administration approval in 2011. The procedure involves the replacement of a severely stenosed native or bioprosthetic aortic valve with a specially constructed valvular prosthesis that is mounted onto a stent, without the use of cardiopulmonary bypass and the complications of a major open surgical procedure. TAVR has been performed mostly in elderly patients with multiple comorbidities or who have undergone previous cardiac surgery. The most commonly used access routes are the femoral artery (transfemoral) or the cardiac apex (transapical), but the transaortic and transubclavian approaches are also used with varying frequency. Conscious sedation may be used in patients undergoing transfemoral TAVR, but the use of general anesthesia has not been shown to carry greater risk and permits the use of transesophageal echocardiography to assist in valve positioning and diagnose complications. Cardiovascular instability during TAVR is relatively common, necessitating invasive monitoring and frequent use of vasoactive medications. Complications of the procedure are still relatively common and the most frequent is vascular injury to the access sites or the aorta. Cardiovascular collapse may be the result of major hemorrhage pericardial effusion with tamponade or coronary occlusion due to incorrect valve placement. Persistent hypotension, myocardial stunning, or injury requiring open surgical intervention may necessitate the use of cardiopulmonary bypass, the facilities for which should always be immediately available. Ongoing and planned trials comparing conventional surgery with TAVR in lower risk and younger patients should determine the place of TAVR in the medium- to long-term future.
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PMID:Controversies and complications in the perioperative management of transcatheter aortic valve replacement. 2523 91